Regioselective Synthesis of Naphtho-fused Heterocycles via Palladium(0)-Catalyzed Tandem Reaction of N-Tosylhydrazones.

We have developed a palladium(0)-catalyzed tandem process which involves the cross-coupling reaction of N-tosylhydrazones with dibromide compounds followed by a sequence of intramolecular 5- exo-trig, 3- exo-trig cyclization, ring opening, and β-hydride elimination to produce 6- endo-trig cyclized products. The strategy was successfully applied for the regioselective synthesis of substituted benzo[ b]naphtho[2,1- d]thiophenes, naphtho[1,2- b]benzofurans, and benzo[ a]carbazoles in moderate to excellent yields. [ABSTRACT FROM AUTHOR]